Infinite loop on 'getline' in Visual Studio 2010 - c++

Question

I am working through some C++ exercises in Visual Studio 2010, and I keep having problems with an infinite loop which occurs when I try to terminate a standard in stream with "CTRL-Z", when using the getline() function. Here is the relevant bit of code....
// find all the lines that refer to each word in the input
map<string, vector<int> >
xref(istream& in,
vector<string> find_words(const string&) = split)
{
string line;
int line_number = 0;
map<string, vector<int> > ret;
// read the next line
while (getline(in, line)) {
++line_number;
// break the input line into words
vector<string> words = find_words(line);
// remember that each word occurs on the current line
for (vector<string>::const_iterator it = words.begin();
it != words.end(); ++it)
ret[*it].push_back(line_number);
}
return ret;
}
...instead of kicking me out of the while loop, the program goes into an infinite loop printing a random integer. I'm pretty sure this is something specific to the Windows environment that I'm missing. Here's the entire code...
#include <algorithm>
#include <cctype>
#include <string>
#include <vector>
#include "split.h"
using std::find_if;
using std::string;
using std::vector;
using std::isspace;
// `true' if the argument is whitespace, `false' otherwise
bool space(char c)
{
return isspace(c);
}
// `false' if the argument is whitespace, `true' otherwise
bool not_space(char c)
{
return !isspace(c);
}
vector<string> split(const string& str)
{
typedef string::const_iterator iter;
vector<string> ret;
iter i = str.begin();
while (i != str.end()) {
// ignore leading blanks
i = find_if(i, str.end(), not_space);
// find end of next word
iter j = find_if(i, str.end(), space);
// copy the characters in `[i,' `j)'
if (i != str.end())
ret.push_back(string(i, j));
i = j;
}
return ret;
}
#include <map>
#include <iostream>
#include <string>
#include <vector>
#include "split.h"
using std::cin; using std::cout;
using std::endl; using std::getline;
using std::istream; using std::string;
using std::vector; using std::map;
// find all the lines that refer to each word in the input
map<string, vector<int> >
xref(istream& in,
vector<string> find_words(const string&) = split)
{
string line;
int line_number = 0;
map<string, vector<int> > ret;
// read the next line
while (getline(in, line)) {
++line_number;
// break the input line into words
vector<string> words = find_words(line);
// remember that each word occurs on the current line
for (vector<string>::const_iterator it = words.begin();
it != words.end(); ++it)
ret[*it].push_back(line_number);
}
return ret;
}
int main()
{
// call `xref' using `split' by default
map<string, vector<int> > ret = xref(cin);
// write the results
for (map<string, vector<int> >::const_iterator it = ret.begin();
it != ret.end(); ++it) {
// write the word
cout << it->first << " occurs on line(s): ";
// followed by one or more line numbers
vector<int>::const_iterator line_it = it->second.begin();
cout << *line_it; // write the first line number
++line_it;
// write the rest of the line numbers, if any
while (line_it != it->second.end()) {
cout << ", " << *line_it;
++line_it;
}
// write a new line to separate each word from the next
cout << endl;
}
return 0;
}

Answer 1

I think instead of trying to make this work, I'd start by writing code I could understand (and for me to understand it, the code has to be fairly simple):
#include <map>
#include <iostream>
#include <string>
#include <vector>
#include <sstream>
#include <iterator>
#include "infix_iterator.h"
typedef std::map<std::string, std::vector<unsigned> > index;
namespace std {
ostream &operator<<(ostream &os, index::value_type const &i) {
os << i.first << ":\t";
std::copy(i.second.begin(), i.second.end(),
infix_ostream_iterator<unsigned>(os, ", "));
return os;
}
}
void add_words(std::string const &line, size_t num, index &i) {
std::istringstream is(line);
std::string temp;
while (is >> temp)
i[temp].push_back(num);
}
int main() {
index i;
std::string line;
size_t line_number = 0;
while (std::getline(std::cin, line))
add_words(line, ++line_number, i);
std::copy(i.begin(), i.end(),
std::ostream_iterator<index::value_type>(std::cout, "\n"));
return 0;
}
As (more or less) usual, this needs the infix_ostream_iterator I've posted elsewhere.